A5974ADTR STMicroelectronics, A5974ADTR Datasheet - Page 32

• Manufacturer Part Number: A5974ADTR
• Description: IC REG SW STEP-DOWN 2A 8SOIC
• Manufacturer: STMicroelectronics
• Series: -r
• Type: Step-Down (Buck), PWMr

Specifications of A5974ADTR

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 1.235 V ~ 35 V
• Current - Output: 2A
• Frequency - Switching: 500kHz
• Voltage - Input: 4 V ~ 36 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width) Exposed Pad
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 497-11423-2

Application information
32/49
the inductor and the V
to the inductor is instead maximized as approximately equal to V
So,
Equation 31
considering T
Equation 32
considering that f
In case a short-circuit at the output is applied, and V
controlled in most of the applications (see
short-circuit condition for an extended period, the external components (mainly the inductor
and diode) must be selected based on this value.
In case the V
does not compensate the current increase during T
example of a power-up phase with V
current escalates and the balance between
higher than the current limit. This must be taken into account in particular to avoid the risk of
an abrupt inductor saturation.
Figure 18. Short-circuit current V
Equation 29
Δ
I
L TOFF
IN
ON
is very high, it could occur that the ripple current during T
, which has already been reduced to its minimum.
and the
SW
Δ
=
I
L TON
has already been reduced to one third of the nominal.
–
------------------------------------------------------------- - 3 T
FW
(
V
D
30
of the free-wheeling diode) while during T
+
=
V
in overcurrent conditions can be simplified to:
V
----------------------------------------------------------------- - T
out
Doc ID 018762 Rev 1
IN
L
–
+
(
DCR
DCR
IN
IN
L
L
= V
L
= 12 V
+
I ⋅
R
)
Figure
IN MAX
(
DS(on)
Equation 31
⋅
SW
) I ⋅
18). When the application must sustain the
= 36 V where
)
(
ON
≅
IN
–
------------------------------------------------------------- - 12μs
ON MIN
(Equation
(
= 12 V, the inductor current is
V
D
and
+
)
V
≅
32
out
V
-------- - 250ns
L
L
Δ
IN
+
occurs at a current slightly
31).
IN
IL TON
(
DCR
.
ON
Figure 20
, the voltage applied
L
>
I ⋅
)
OFF
Δ
)
(
IL TOFF
(Equation
shows an
)
A5974AD
so the
32)